Cost Estimates: Stress Improvement Remedies for Savannah River Reactor Process Water Pipe Welds.

摘要

The process water pipes in the Savannah River reactors were made of Type 304 stainless steel. This steel becomes susceptible to intergranular stress corrosion cracking (IGSCC) when sensitized as by welding. IGSCC may initiate in locations under residual or applied tensile stress in the presence of impure water such as the moderator. One recommendation from the 1986 ES and H audit was for further evaluation of the application of stress improvement (SI), either induction heating stress improvement (HSI) or heat sink welding (HSW), to preclude further cracks and leaks in susceptible welds in the process water piping. In our response to this ES and H recommendations, we stated that there was no safety reason to consider such action, but that we would evaluate the operational cost-benefit of remedial treatment of the welds. Mechanical stress improvement (MSIP), weld overlay (WO) and Pipelock were evaluated also. All of the welds in the process water systems which join Type 304 stainless steel are potential sites for IGSCC. Therefore, any of the approved treatments would be of potential benefit by eliminating or reducing the tensile stress necessary for IGSCC. 9 refs., 3 tabs. (ERA citation 14:011069)